diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,8 @@
 # hw-prim
-[![v0.0-branch](https://circleci.com/gh/haskell-works/hw-prim/tree/v0.0-branch.svg?style=svg)](https://circleci.com/gh/haskell-works/hw-prim/tree/v0.0-branch)
+[![0.0-branch](https://circleci.com/gh/haskell-works/hw-prim/tree/0.0-branch.svg?style=svg)](https://circleci.com/gh/haskell-works/hw-prim/tree/0.0-branch)
 
 Primitive types library.
+
+To build with GHC 8: `nix-build --arg compiler \"ghc801\"`
+
+Report dependency build errors: https://github.com/haskell-infra/hackage-trustees
diff --git a/hw-prim.cabal b/hw-prim.cabal
--- a/hw-prim.cabal
+++ b/hw-prim.cabal
@@ -1,5 +1,5 @@
 name:                   hw-prim
-version:                0.0.2.0
+version:                0.0.3.0
 synopsis:               Primitive functions and data types
 description:            Please see README.md
 homepage:               http://github.com/haskell-works/hw-prim#readme
@@ -12,14 +12,14 @@
 stability:              Experimental
 build-type:             Simple
 extra-source-files:     README.md
-cabal-version:          >= 1.10
+cabal-version:          >= 1.22
 
 executable hw-prim-example
   hs-source-dirs:       app
   main-is:              Main.hs
   ghc-options:          -threaded -rtsopts -with-rtsopts=-N -Wall -msse4.2
   build-depends:        base                          >= 4          && < 5
-                      , hw-prim                       >= 0.0.1
+                      , hw-prim
   default-language:     Haskell2010
 
 library
@@ -66,5 +66,5 @@
     Default-Language: Haskell2010
     Build-Depends:      base                          >= 4          && < 5
                       , criterion
-                      , hw-prim                       >= 0.0.1
+                      , hw-prim
                       , vector
diff --git a/src/HaskellWorks/Data/Vector/VectorLike.hs b/src/HaskellWorks/Data/Vector/VectorLike.hs
--- a/src/HaskellWorks/Data/Vector/VectorLike.hs
+++ b/src/HaskellWorks/Data/Vector/VectorLike.hs
@@ -26,6 +26,7 @@
   vTake :: Count -> v -> v
   vIndex :: v -> Position -> Elem v
   vSlice :: Position -> Position -> v -> v
+  vUncons :: v -> Maybe (Elem v, v)
 
 instance VectorLike String where
   type Elem String = Char
@@ -40,6 +41,9 @@
   vTake = take . fromIntegral
   vIndex v (Position i) = v !! fromIntegral i
   vSlice (Position i) (Position j) = take (fromIntegral j) . drop (fromIntegral i)
+  vUncons s = case s of
+    (x:xs)  -> Just (x, xs)
+    _       -> Nothing
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -51,6 +55,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike BS.ByteString where
   type Elem BS.ByteString = Word8
@@ -67,6 +72,7 @@
   vTake = BS.take . fromIntegral
   vIndex v (Position i) = BS.index v (fromIntegral i)
   vSlice (Position i) (Position j) = BS.take (fromIntegral j) . BS.drop (fromIntegral i)
+  vUncons = BS.uncons
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -78,6 +84,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DV.Vector Word8) where
   type Elem (DV.Vector Word8) = Word8
@@ -93,6 +100,7 @@
   vTake = DV.take . fromIntegral
   vIndex v (Position i) = DV.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DV.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DV.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -104,6 +112,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DV.Vector Word16) where
   type Elem (DV.Vector Word16) = Word16
@@ -119,6 +128,7 @@
   vTake = DV.take . fromIntegral
   vIndex v (Position i) = DV.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DV.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DV.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -130,6 +140,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DV.Vector Word32) where
   type Elem (DV.Vector Word32) = Word32
@@ -145,6 +156,7 @@
   vTake = DV.take . fromIntegral
   vIndex v (Position i) = DV.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DV.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DV.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -156,6 +168,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DV.Vector Word64) where
   type Elem (DV.Vector Word64) = Word64
@@ -171,6 +184,7 @@
   vTake = DV.take . fromIntegral
   vIndex v (Position i) = DV.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DV.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DV.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -182,6 +196,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DVS.Vector Word8) where
   type Elem (DVS.Vector Word8) = Word8
@@ -197,6 +212,7 @@
   vTake = DVS.take . fromIntegral
   vIndex v (Position i) = DVS.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DVS.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DVS.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -208,6 +224,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DVS.Vector Word16) where
   type Elem (DVS.Vector Word16) = Word16
@@ -223,6 +240,7 @@
   vTake = DVS.take . fromIntegral
   vIndex v (Position i) = DVS.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DVS.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DVS.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -234,6 +252,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DVS.Vector Word32) where
   type Elem (DVS.Vector Word32) = Word32
@@ -249,6 +268,7 @@
   vTake = DVS.take . fromIntegral
   vIndex v (Position i) = DVS.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DVS.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DVS.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -260,6 +280,7 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}
 
 instance VectorLike (DVS.Vector Word64) where
   type Elem (DVS.Vector Word64) = Word64
@@ -275,6 +296,7 @@
   vTake = DVS.take . fromIntegral
   vIndex v (Position i) = DVS.unsafeIndex v (fromIntegral i)
   vSlice (Position i) (Position j) = DVS.unsafeSlice (fromIntegral i) (fromIntegral j)
+  vUncons s = if DVS.length s == 0 then Nothing else Just (s !!! 0, vDrop 1 s)
   {-# INLINE (!!!)     #-}
   {-# INLINE vConcat   #-}
   {-# INLINE vEmpty    #-}
@@ -286,3 +308,4 @@
   {-# INLINE vTake     #-}
   {-# INLINE vIndex    #-}
   {-# INLINE vSlice    #-}
+  {-# INLINE vUncons   #-}